As a conventional propeller fan, a propeller fan provided with a plurality of small notches in an outer edge portion of a blade as disclosed, for example, in Japanese Patent Laying-Open No. 2008-157117 (PTD 1) and a propeller fan provided with a notch in a rear edge portion of a blade as disclosed, for example, in Japanese Patent Laying-Open No. 2003-206894 (PTD 2) have been known.
These propeller fans were designed with focus being mainly placed on lowering in noise or improvement in blowing efficiency by suppressing a vortex which is generated in an outer edge portion or a rear edge portion of a blade and flows from a side of a positive pressure surface toward a negative pressure surface (generally referred to as a horseshoe vortex).
As a conventional propeller fan, Japanese Patent Laying-Open No. 2003-206894 (PTD 2) discloses a propeller fan aiming to suppress fluctuation and development of a vortex generated from a blade tip end portion and a blade end portion of the propeller fan, prevent separation over a blade surface, and increase a quantity of wind. The propeller fan disclosed in PTD 2 is constituted of a cylindrical boss and a plurality of blades. A recess is formed at a prescribed position at a rear end of a blade.
Japanese Patent Laying-Open No. 2011-58449 (PTD 3) discloses a propeller fan aiming to greatly contribute to energy saving and design for resource saving. The propeller fan disclosed in PTD 3 has two or three blades and a coupling portion connecting the blades to each other. A consecutive disposition portion has a surface like a blade surface, and exhibits a function to send wind in a forward direction around a center of rotation of the blade.
Japanese Patent Laying-Open No. 2004-293528 (PTD 4) discloses a propeller fan aiming to improve aerodynamic performance and lower noise and power consumption. When a vane is cut along a prescribed plane in a direction of an axis of rotation thereof in the propeller fan disclosed in PTD 4, a smooth convex curve which is convex toward upstream is obtained.
Japanese Patent Laying-Open No. 2000-54992 (PTD 5) discloses a propeller fan aiming to lessen separation of a flow of an air current and to achieve both of improvement in blowing performance and lowering in noise during blowing. In the propeller fan disclosed in PTD 5, a plurality of blades are disposed around a boss portion. Each blade is formed such that its cross-sectional shape is in a streamline shape in both of a circumferential direction and a direction of radius.